Various electric stoves capable of suppressing the production of smoke have been proposed by the present inventor as background conventional technology of the present invention (see, for example, patent literature 1).
This electric stove includes an electric heating element such as a sheathed heater provided at a distance from a position right below a target to be cooked (hereinafter, referred to as a “target to be heated”) and a mirror surface portion for collecting heat rays radiated from the electric heating element to a side below the target to be heated. This mirror surface portion is configured to include a partial elliptical mirror surface portion which has one focus near the electric heating element and reflects the heat rays radiated from the electric heating element, a first reflecting mirror surface portion which is provided below the electric heating element and collects the heat rays reflected by the partial elliptical mirror surface portion to the side below the target to be heated, and a second reflecting mirror surface portion which is provided below the electric heating element and collects the heat rays not reflected by the first reflecting mirror surface portion to the side below the target to be heated.
However, in this electric stove, not all the heat rays radiated from the electric heating element and reflected by the partial elliptical mirror surface portion, the first and second reflecting mirror surface portions are efficiently radiated to a laying member such as a baking rack on which the target to be heated is placed, but there are heat rays accumulated in the electric stove. Since there is a loss in terms of thermal efficiency, the reflection efficiency of the heat rays on the mirror surface portion is far from satisfactory.
Accordingly, the present inventor proposed an electric stove improved to maximally reduce a loss in terms of thermal efficiency by increasing the reflection efficiency of heat rays on a mirror surface portion (see, for example, patent literature 2).
For example, as shown in FIGS. 21 and 22, this electric stove 1 is configured to include an electric heating element 3 arranged at a distance from a position right below targets to be heated W, a first mirror surface portion 5 including a partial elliptical mirror surface portion arranged to surround the electric heating element 3, having one focus near the electric heating element 3 and configured to reflect heat rays radiated from the electric heating element 3, and a second mirror surface portion 7 including a conical mirror surface portion arranged below the electric heating element 3 and configured to collect the heat rays reflected by the first mirror surface portion 5 to a side below the targets to be heated by reflecting them substantially immediately upwardly.
In this improved electric stove 1, the heat rays radiated form the electric heating element 3 are reflected by the first mirror surface portion 5. The heat rays reflected by the first mirror surface portion 5 are reflected immediately upwardly in a substantially vertical direction and collected to the side below the targets to be heated W by the action of the second mirror surface portion 7. Thus, in this electric stove 1, the heat rays can be irradiated to the side below the targets to be heated W with a small number of reflections as compared with conventional electric stoves, for example, as shown in patent literature 1 by reflecting the heat rays reflected by the first mirror surface portion 5 by the second mirror surface portion 7. In this case, the heat rays are less accumulated in an inner side surrounded by the first and second mirror surface portions 5, 7 and effectively collected to the side below the targets to be heated W. Further, less heat rays reflected by the second mirror surface portion 7 escape to a side (outer peripheral side) of this electric stove 1.
Patent Literature 1: Pamphlet of International Publication No. WO 07/102206 (see FIGS. 5, 6).
Patent Literature 2: Pamphlet of International Publication No. WO 09/130756 (see FIGS. 5 to 9).